AbstractCache.h++

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/* ---------------------------------------------------------------------------
   commonc++ - A C++ Common Class Library
   Copyright (C) 2005-2014  Mark A Lindner

   This file is part of commonc++.

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with this library; if not, write to the Free
   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   ---------------------------------------------------------------------------
*/

#ifndef __ccxx_AbstractCache_hxx
#define __ccxx_AbstractCache_hxx

#include <set>
#include <utility>

#include <commonc++/Common.h++>

namespace ccxx {

template<typename K, typename T> class AbstractCache
{
 public:

  virtual ~AbstractCache();

  virtual T* get(const K& key) = 0;

  inline T *operator[](const K& key)
  { return(this->get(key)); }

  bool contains(const K& key) const;

  virtual void clear();

  inline uint_t getMaxSize() const
  { return(_maxSize); }

  inline uint_t getSize() const
  { return(_map.size()); }

  inline bool isEmpty() const
  { return(_map.empty()); }

  inline bool isFull() const
  { return(_map.size() == _maxSize); }

 protected:

  AbstractCache(uint_t maxSize);

  virtual void onRemove(const K& key, T* item);

  uint_t _maxSize;

  struct Link
  {
    Link(K key, T* data = NULL)
      : key(key)
      , data(data)
      , prev(NULL)
      , next(NULL)
    { }

    ~Link()
    {
      delete data;
    }

    K key;
    T* data;
    Link* prev;
    Link* next;
  };

  typedef Link LinkType;

  struct KeyCompare
  {
    bool operator()(const Link* key1, const Link* key2) const
    { return(key1->key < key2->key); }
  };

  void _link(Link* link) const;
  void _unlink(Link* link) const;

  typedef std::set<Link*, KeyCompare> MapType;
  mutable MapType _map;
  mutable Link* _head;
  mutable Link* _tail;
};

#include <commonc++/AbstractCacheImpl.h++>

} // namespace ccxx

#endif // __ccxx_AbstractCache_hxx